Rate based on quality

 Hi,

We purchase acid from a supplier with rate based on agreed quality. But this rate will change proportionately with the variance in concentration. For example the rate is $100/ Ltrs. with the agreed concentration of 34% and I recieve 40 Ltrs. My payable amount will be caculated as follows:

Rate x received quantity X (Actual Concentration / Agreed Concentration)

If the concentration is 34% then payable amount will be:

100 x 40 x (34/34) = 4,000.00

If the concentration is 30% then payable amount will be:

100 x 40 x (30/34) = 3,529.41

Note that in both cases we will recieve 40 Ltrs.

I will appreciate if someone can guide as to how this can be managed in Oracle procurement? (Version R12)